I LOVE THIS SCENE, WITH DEAN AND JACK IN THE BUNKER. Because Dean's apparently just back from an "all-night" run to wherever Bobby and Mary are shacked up. Jack is caffeinating and no one else seems to be around, so I feel like it must be 4 or 5AM. (It's already light in Sam and Charlie's timezone when Dean calls, but since they're in Tennessee and the Bunker is in Kansas, that checks out. And it's purply dawn at the diner by the time Dean and Jack hit Nebraska. Even though someone apparently wants a sandwich and two Cokes for breakfast... XDD)
Anyway, it's not that Dean and Jack are alone in the Bunker in that scene, and everyone else decided to all go out on a hunt at the exact same time--it's that most everyone is probably asleep. There are probably some stragglers in the common areas between the door and the kitchen that Dean just ignored--random bodies out there reading a book or whittling small wooden animals or whatever it is the Cone World people like to do. When Jack says Sam wanted someone to be there for Dean when he got back, Sam meant someone specifically not all their random Cone World people.
Which suggests to me that although Dean's now been back for a decent stretch of time (what, like three episodes?) and in spite of his "oh yeah I do like people" epiphany post-hanging out with that guy in 14x04 "Mint Condition", he's probably still made zero real efforts to become part of the new fabric of the Bunker and engage with any of these people.
And like, what business could Dean possibly have had with Mary and Bobby? My best guess is an extremely overcourteous supply run, borne more from Dean's desire to be somewhere not the Bunker moreso than Mary and Bobby's inability to get their own damn food. I can see that playing out as like, Dean not-seriously complaining for the thousandth time that there are like ten different apps that can now deliver food--even from joints that don't do delivery--but they mean fuck-all since they can't exactly deliver to the Bunker, now can they. Sam knows what the idle complaint is really about--Dean's discomfort at the Bunker being filled with strangers. Even though Dean's not really complaining, in the sense that he actively wants anything to change. They are refugees from an angelic war in another universe, after all. Dean's not gonna whine about them sharing his roof. He's just going to be distressed about it the entire time.
Which sucks for Sam, because he feels like he is somehow responsible for "sullying" the Bunker for Dean. Somehow. Because Dean was the one who first liked it so much and made it home and now Dean's not comfortable there and Sam can tell half the time he's looking for a reason to leave and Sam knows none of this is his fault--or even something where any sort of blame is attached at all--but Sam feels like it's there anyway, and of course it's attached to him.
And then Dean jumps from his delivery app grumblings to "oh hey, I should haul a crate of supplies up to the cabin for Mom and Bobby" because it's something that sounds vaguely productive, even as it's extremely logistically illogical and also overbearing. And Sam looks at him like, "Dean, That's extremely logistically illogical and also overbearing" and Dean shrugs back like, "And... what's the problem? Literally my MO."
So Dean goes off and does that--pointedly by himself, without wanting Sam along. Dean makes some comment about "me time" (rather than "we time") and then another joking-but-not-altogether-sensitive comment about Sam's fiefdom Sam has to run (there is a queue of other people wanting to confer with Sam at that very moment--a queue Dean uses to slip away before Sam can confront him again). and Sam suffers for it, because he is very definitely not over the cycle of months he spent trying to track down Michael, not knowing if he'd ever see his brother again, and in no way can he feel secure and comfortable in the idea that Dean is actually back. His return was so abrupt and so full of unanswered questions Dean's presence now is less a comfort than it is Sam's constant state of anxiety that Dean is going to be stripped away at any moment. Of course, his absence is still worse. Part of Sam can't really trust that Dean won't just walk out on his own--do some bizarre supply run to Mary and Bobby and then decide he's going to wander a while. Part of Sam can't really trust that Dean won't pull a Mary.
Even though Sam knows Dean won't. He knows this. He also knows Dean's not going to do anything insane if Sam's not waiting in the Bunker for him, and Dean's not going to be incapacitated by his devastation if no one is waiting in the Bunker for him. Sam knows. But panic doesn't follow rationality.
And besides, Sam figures. Every gesture doesn't have to be life and death. You're not supposed to live life desperately applying tourniquets to every situation (even if that's how he feels, generally speaking). Sometimes it's just nice to come home, and have someone dumping half the world's supply of sugar into a coffee cup. It's just nice.
I feel like Sam's struggling with the good he feels he's doing with his tutelage of these new Men of Letters/hunters--even though (or maybe especially because) of Bobby's tacit acknowledgement of Sam's ability to do it well. In going off with Mary, Bobby did essentially give the reins of leadership over to Sam, and rescind his earlier criticisms. Dean is probably part of it re: the Bunker being full of strangers--a larger part than Sam would like to admit, because if Sam gave in to his every impulse, his first would be to drop all of these people (all of them) if he thought it would help Dean. Even though both he and Dean know that is very stupid and very wrong. Because no matter how many times they say and act otherwise, if it's brother vs. the world, brother comes out on top. Knowing that it's wrong doesn't make it less true. And Dean is part of it again because as far as Sam's formative conception of how the world works, Dean is the one with investments in the group, in family. In keeping everyone together. And that's not one of Dean's priorities right now--more specifically, not an overwhelming identifier of Dean's very being. Whether Dean is in some dramatically dark space worthy of Sam's intense concern or Dean's just tired and Done With it in a neutral undramatic sort of way, he's not helping Sam's sense of security. When Sam doesn't feel secure, his coping mechanism is to narrativize and sometimes speechify and pontificate (which Charlie got to witness and recognize and bear the brunt of, lol). She humors him.
Part of this is painful, because they are both experiencing high stress/anxiety--the kind that simmers and endures and doesn't relent; not the kind that explodes and acts. But there's some light there, too. Because even as they continually find themselves in those life states where the best they feel like they can really hope for is an opportunity to think, "Well, thank god for all these tourniquets!" here's Sam still believing and trying to make real his feeling that they don't have to settle for simply surviving. It is okay to seek comfort as well, and to make space for those allowances. Comfort is not a luxury; it is a just desert. Maybe, Sam thinks, he can call that optimism.
And so Jack, and his sugar with coffee. Waiting for Dean to come home.
Also, not to disrupt the solemnity of that ending, but I loved Dean's... soft taco? What did he even put in it? It had to have been cheese but the strands were SO long it looked like butternut squash noodles. But since I doubt Dean would think to himself, "Man, you know what I could really go for right now? A cold tortilla filled with butternut squash" it had to have been cheese, right?
Which begs two questions:
1) WHO IN THE BUNKER SHREDDED THE CHEESE SO CAREFULLY, THE LONG WAY DOWN THE BLOCK.
2) Did Dean heat it up or did he just eat a tortilla absolutely bursting with shredded cheese stone-ass cold??
These are important questions.